A 15.2 kg block dragged over rough horizontal surface by constant force of 124N acting at an angle of 34.9 degrees above the horizontal. The block is displaced 37.8m. The coefficient of kinetic friction is .171. Acceleration is 9.8 m/s^2.

Question

Find the work done by the 124N force.
Find the magnitude of the work done by the force of friction.
Find the work done by the normal force.

Answer 1

Well first of all the third question:
The Normal Force DOES NO WORK because there is no motion in the direction of the force. Period, like why did you ask !!!!

124 N has 124 cos 34.9 in the direction of motion
It moves 37.8 meters
so
work = 124 * 37.8 * cos 34.9 Joules

friction force:
normal force = 15.2*9.8 - 124 sin 34.9
friction force = 0.171* normal force
so
work against friction = 37.8 * friction force
It is negative but it only asked for the magnitude.